The present invention relates to an organic EL display device, and, more particularly, to an organic EL display device in which each pixel region is partitioned by a bank film from other pixel regions that are arranged close to the pixel region.
For example, an active-matrix type organic EL display device includes, on a surface of a substrate thereof, gate signal lines, which extend in the x direction and are arranged in parallel in the y direction, and drain signal lines, which extend in the y direction and are arranged in parallel in the x direction, wherein rectangular regions which are bounded by these signal lines define pixel regions. Each pixel region includes a switching element, which is turned on in response to a scanning signal received from the one gate signal line, and a pixel electrode to which a video signal is supplied from the one drain signal line through the switching element. Here, a counter electrode is stacked over an upper surface of the pixel electrode by way of a light emitting material layer. A signal which becomes a reference with respect to the video signal is supplied to the counter electrode. A current is made to flow into the light emitting material layer through the above-mentioned respective electrodes, and the light emitting material layer emits light in response to this current. The emission of light is visible through one electrode (the light transmitting conductive film) of the above-mentioned respective electrodes.
Here, although the above-mentioned signal lines and electrodes are formed by selective etching using photolithography, the light emitting material layer is usually formed using a so-called vacuum evaporation shadow mask. This is because, when the light emitting material layer contains moisture or the like, the fight emitting material layer is easily degenerated.
Further, the light emitting material layer is in a liquid state when it is applied to the substrate, and, hence, a bank film made of resin, for example, is preliminarily formed for partitioning each pixel region from other pixel regions arranged close to the pixel, and the light emitting material layer is filled in the inside of an opening portion formed in the bank film (see the following patent literature 1).
[patent literature 1]
Japanese Unexamined Patent Publication 2000-176660.